As mobile devices improve and include more enhanced capabilities, mobile devices have evolved to act as Internet Protocol (IP) devices. One such system, e.g., a system employing IP Multimedia services (IMS) sessions, is illustrated in FIG. 1, wherein a traditional signaling bearer architecture for a local media session is illustrated. The traditional IMS session is created between a User Equipment (UE) 102 and a remote end 104, thereby enabling the UE 102 to access media flows, such as media flow 106. The standard IMS signaling flow, illustrated in FIG. 1 by the dotted line 108, extends between a Call Session Control Function (CSCF) 110, a Service Centralization Continuity Application Server (SCC AS) 112, and a Telephony Application Server (TAS) 114 (and/or other application servers).
Generally, the CSCF 110 processes session initiation protocol (SIP) signaling packets in the IMS system, and the application servers host and execute a variety of services. In one embodiment, the SCC AS 112 operates in a Back-to-Back User Agent (B2BUA) mode wherein it acts as an SIP element to mediate SIP signaling between the UE 102 and the remote end 104. In the embodiment illustrated in FIG. 1, the SCC AS 112 establishes an access leg using IMS procedures between the SCC AS 112 and the CSCF 110 on the UE 102 side and establishes a remote leg using IMS procedures to the CSCF 110 on the remote end 104 side. Other application servers, such as the TAS 114 illustrated in FIG. 1, may be executed on the remote leg as part of standard service execution logic at the CSCF 110.
The result of an IMS session established as discussed above is a media flow 106 and a session control signaling flow 108 established between the UE 102 and the remote end 104. Unfortunately, however, the media flow 106 and the session control signaling flow 108 are tied to the same device, thereby not allowing the media flow 106 to be sent to a different device or controlled by a different device. For example, if a user is interested in watching a video, current implementations require that the media flow 106, e.g., the video, be sent to the same device, e.g., a wireless telephone, as is controlling the video. Moreover, when a media flow 106 is transferred to another device, both the session control signaling flow 108 and the media flow 106 are transferred to the same device. This situation is not always convenient or desired by the user, who may want to control the media flow 106 via one device, but watch the video on a different device, such as a computer monitor or television.
Furthermore, some IP devices are stationary, such as hardware IP phones, video-conferencing units, embedded devices, and the like. While these IP devices may be stationary, these IP devices may allow more convenience of use and additional capabilities than other more mobile IP devices, but maintain session control on the mobile IP device. As a result, it may be desirable to separate the media flow from the session control signaling flow.
Thus, there is a need for a method and system that allows the media flow to be controlled by a separate device, thereby allowing the moving of active multimedia sessions between IP devices to allow mobile and stationary devices to be used concurrently or interchangeably in mid-session, combining their advantages into a single “virtual device.”